At today's International Solid State Circuit Conference, imec
and Holst Centre report an analog-signal processor ASIC (application-specific
integrated circuit) - in short ASP - that reduces the overall power consumption
of an ambulatory heart activity signal monitoring systems by more than 5 times.
This is a major step towards autonomous wireless sensor systems powered, which
constantly monitor the patient's health for diagnosis or chronic illness.
Die photograph of imec and Holst Centre’s 30µW analog signal processor ASIC for biopotential signal monitoring.
In today's biomedical wireless sensor systems, a lot of power consumption
is wasted in the DSP (digital signal processor) or radio by continuously processing
biopotential signals (e.g. ECG or electrocardiogram), or transmitting raw data
over the wireless link. And, today's ambulatory biomedical sensor systems
also suffer from motion artifacts which affects the robustness of detection
algorithms and demands even more processing power.
The innovative ASP, developed within imec's and Holst Centre's
HUMAN++ program, uses an adaptive sampling scheme based on activity detection.
This reduces the amount of data which needs to be processed by the DSP or transmitted
by the radio. By preprocessing the signal, a simplified DSP can be used for
accurate R-peak detection resulting in lower power consumption of the DSP. Motion
artifacts are detected by continuously monitoring the electrode-tissue impedance.
The impedance monitoring can also be used for ensuring signal integrity by continuously
checking the electrode connectivity.
The ASP has a record low power consumption of only 30µW operating from
2V. It consists of an ECG readout channel, two quadrature readout channels for
continuous-time monitoring of electrode-tissue impedance, and two quadrature
readout channels for tracking signal fluctuations in a specific frequency band.
The ASP also includes an activity detector that senses the frequency content
of the ECG signal and adapts the sampling rate of the integrated ADC (analog
to digital convertor) for the digitization of the ECG signal. The ASP stage
reduces the power consumption of the DSP and wireless transmission by 11 and
6 times respectively. This results in an overall system power dissipation below
300µW for the complete wireless heart activity signal monitoring system
which is more than 5 times more power efficient than its predecessors. This
power budget also includes the additional functionality of continuous-time electrode-tissue
contact impedance measurement.
“Within the Human++ program, imec and Holst Centre develop solutions
for an efficient and better healthcare. Self-powered intelligent body area networks
with wireless sensors promise to be a solution for more comfortable healthcare
systems. This breakthrough is a major step towards constant ambulatory monitoring
of people using energy harvesting, which increases the comfort level of patients
and is a cost- and time-efficient alternative for current monitoring systems;”
said Bert Gyselinckx, general manager imec the Netherlands at Holst Centre.
Industry can get access to this technology by joining the Human++ program as
research partner or by licensing agreements for further product development.
At this week's International Solid State Circuit Conference, imec and Holst
Centre present their newest breakthroughs in ultra-low power design for wireless
communications and wireless sensor networks and in organic electronics with
an impressive number of contributions including 10 reviewed publications and
6 contributions to tutorials and workshops.
Imec performs world-leading research in nano-electronics. Imec leverages its
scientific knowledge with the innovative power of its global partnerships in
ICT, healthcare and energy. Imec delivers industry-relevant technology solutions.
In a unique high-tech environment, its international top talent is committed
to providing the building blocks for a better life in a sustainable society.